Radiation Oncology Department, Institut Català d'Oncologia, Hospital Germans Trias i Pujol, Badalona, Barcelona, Spain.
Clin Transl Oncol. 2012 Feb;14(2):132-7. doi: 10.1007/s12094-012-0772-8.
The aim of this study is to determine the interobserver variability (IV) between radiation oncologists (RO) in target volume delineation for postoperative gastric cancer (GC) radiotherapy planning.
Four physicians were asked to delimitate clinical target volume (CTV) on the same 3D CT images in 9 postoperative radiochemotherapy GC patients. Instructions were given to include tumour bed, remaining stomach, anastomosis, duodenal loop and local lymph nodes. The principal variable was spatial volume discrepancy between the main observer (called "A") and other observers (all called "B"), which were compared using the mathematical formula A⌣B/A⌢B, applied to the 3D CT images using Boolean operators. Analysis of variance with two random effects (observers and patients) was performed.
Mean volumes were 1410 cm(3) for OBA, 1231 cm(3) for OB2, 734.6 cm(3) for OB3 and 1350 cm(3) for OB4. Discrepancies were 519.9±431.6 cm(3) for OB2, 652.1±294.36 cm(3) for OB3 and 225.90±237.07 cm(3) for OB4. Standard deviation ascribed to patients as random effect was 898.6 cm(3) and that ascribed to observers was 198.10 cm(3), considered as a statistically significant difference.
A significant IV in target delineation that can be attributed to many factors depends more on patients' characteristics than RO delineating decisions.
本研究旨在确定术后胃癌（GC）放射治疗计划中，放射肿瘤学家（RO）在靶区勾画方面的观察者间变异性（IV）。
要求 4 名医师在 9 例接受术后放化疗的 GC 患者的 3DCT 图像上勾画临床靶区（CTV）。CTV 勾画的指导方针包括肿瘤床、残余胃、吻合口、十二指肠袢和局部淋巴结。主要变量是主观测者（称为“A”）和其他观察者（均称为“B”）之间的空间体积差异，通过使用布尔运算符在 3DCT 图像上应用数学公式 A⌣B/A⌢B 进行比较。采用双随机效应（观察者和患者）方差分析。
OBA 的平均体积为 1410cm³，OB2 为 1231cm³，OB3 为 734.6cm³，OB4 为 1350cm³。OB2 的差异为 519.9±431.6cm³，OB3 为 652.1±294.36cm³，OB4 为 225.90±237.07cm³。作为随机效应归因于患者的标准差为 898.6cm³，归因于观察者的标准差为 198.10cm³，认为存在统计学差异。
靶区勾画的显著 IV 可能归因于许多因素，更多地取决于患者的特征，而不是 RO 的勾画决策。
